HID: uhid: invert report_done and make non-atomic

All accesses to @report_done are protected by qlock (or report-contexts).
No need to use an atomic.

While at it, invert the logic and call it "report_running". This is
similar to the uhid->running field and easier to read.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>